I put in gas, electric, water and phone in one trench. Electric has to be on the bottom and 6 feet down, then gas which has to be 12 inches away from the electric, then water which has to be 12 inches away from the gas and then phone and any other low voltage.
I just dig a 6 foot trench.
Electric has to come out and see the wire in the conduit before I can bury it. The rest no one seems to care about.